1. Field of the Invention
The present invention relates to a high frequency heating device, such as microwave ovens, and, in particular, to a high frequency heating device including an exterior switch which opens the power supply circuit of the device when its removable exterior for covering an outer surface of the device is removed.
2. Description of the Related Art
High frequency heating devices generally used include a portion which has a high voltage of approximately three to four kV in the machinery chamber and they are provided with an exterior switch which opens the power supply circuit when the exterior for covering an outer surface of the devices is removed so that servicing people or the like do not get an electric shock when they work on maintenance of the devices. For example, Japanese Patent Publication No. 58-28888 discloses a high frequency heating device having an exterior switch turned on and off by the exterior.
FIG. 15 is a partially exploded, perspective view showing a high frequency heating device disclosed in Japanese Patent Publication No. 58-28888. In a microwave oven shown in FIG. 15 as one example of the high frequency heating device, an exterior 902 covers an outer surface of the body including a door 903 provided at the front side of the device and is fixed to the body by a screw 904.
An exterior switch 905 which opens and closes the power supply circuit of the device closes the contact point when one wall surface of exterior 903 presses an actuator 906. That is, exterior switch 905 closes the power supply circuit when exterior 903 is mounted, and it opens the power supply circuit when exterior 903 is removed.
When exterior 903 is removed, however, actuator 906 can be inadvertently pressed due to careless behavior of servicing people or the like. More specifically, since exterior switch 905 is structured to be operated only by flat exterior 906, the contact point of the exterior switch can be closed with exterior 903 removed when actuator 906 is inadvertently pressed. This means that for microwave oven 900, the power supply circuit can be closed with exterior 903 removed, and maintenance of the device by servicing people or the like is considerably dangerous.
Furthermore, the screws which fix the exterior to the body can be removed using commercially available drivers, and one without technical knowledge can readily remove the exterior.
Thus, it is desirable that the exterior switch more surely keeps the power supply circuit open in such a heating device when its exterior is removed.